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---
id: 587d7fa9367417b2b2512bcf
title: Dynamically Change the Height of Each Bar
challengeType: 6
---
## Description
<section id='description'>
The height of each bar can be set to the value of the data point in the array, similar to how the <code>x</code> value was set dynamically.
<blockquote>selection.attr("property", (d, i) => {<br> /* <br> * d is the data point value<br> * i is the index of the data point in the array<br> */<br>})</blockquote>
</section>
## Instructions
<section id='instructions'>
Change the callback function for the <code>height</code> attribute to return the data value times 3.
<strong>Note</strong><br>Remember that multiplying all data points by the same constant scales the data (like zooming in). It helps to see the differences between bar values in this example.
</section>
## Tests
<section id='tests'>
```yml
tests:
- text: The first <code>rect</code> should have a <code>height</code> of 36.
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testString: assert($('rect').eq(0).attr('height') == '36', 'The first <code>rect</code> should have a <code>height</code> of 36.');
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- text: The second <code>rect</code> should have a <code>height</code> of 93.
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testString: assert($('rect').eq(1).attr('height') == '93', 'The second <code>rect</code> should have a <code>height</code> of 93.');
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- text: The third <code>rect</code> should have a <code>height</code> of 66.
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testString: assert($('rect').eq(2).attr('height') == '66', 'The third <code>rect</code> should have a <code>height</code> of 66.');
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- text: The fourth <code>rect</code> should have a <code>height</code> of 51.
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testString: assert($('rect').eq(3).attr('height') == '51', 'The fourth <code>rect</code> should have a <code>height</code> of 51.');
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- text: The fifth <code>rect</code> should have a <code>height</code> of 75.
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testString: assert($('rect').eq(4).attr('height') == '75', 'The fifth <code>rect</code> should have a <code>height</code> of 75.');
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- text: The sixth <code>rect</code> should have a <code>height</code> of 54.
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testString: assert($('rect').eq(5).attr('height') == '54', 'The sixth <code>rect</code> should have a <code>height</code> of 54.');
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- text: The seventh <code>rect</code> should have a <code>height</code> of 87.
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testString: assert($('rect').eq(6).attr('height') == '87', 'The seventh <code>rect</code> should have a <code>height</code> of 87.');
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- text: The eighth <code>rect</code> should have a <code>height</code> of 42.
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testString: assert($('rect').eq(7).attr('height') == '42', 'The eighth <code>rect</code> should have a <code>height</code> of 42.');
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- text: The ninth <code>rect</code> should have a <code>height</code> of 27.
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testString: assert($('rect').eq(8).attr('height') == '27', 'The ninth <code>rect</code> should have a <code>height</code> of 27.');
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```
</section>
## Challenge Seed
<section id='challengeSeed'>
<div id='html-seed'>
```html
<body>
<script>
const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
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const w = 500;
const h = 100;
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const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
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svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", (d, i) => i * 30)
.attr("y", 0)
.attr("width", 25)
.attr("height", (d, i) => {
// Add your code below this line
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// Add your code above this line
});
</script>
</body>
```
</div>
</section>
## Solution
<section id='solution'>
```js
// solution required
```
</section>
